I do not think gluten is as harmless as people are making it out to be. I have seen no evidence that this is any trouble for most people. I haven't seen any evidence that this is harmful to the general population; only that some people are allergic to foods with gluten.
No, young children should not be placed on a gluten-free diet as a matter of routine, because for most kids, a little bit of gluten is okay. Unless the child has specific dietary needs, they can eat what the rest of us do. There is no need to restrict their diets as a matter of course.
Although gluten free diets have become something of a fad as of late, the presence of gluten in the diets of growing children is a necessity. Gluten does not do harm to everyone, only those individuals who have that specific allergy. Children need to be exposed to all major macronutrients to grow.
I do not believe young children should be placed on gluten-free diets as a matter of routine. I think limiting children's diets is completely unnecessary. Some people may have celiac disease but that is not representative of the majority of the population. We shouldn't change every diet just because of a few people have problem with gluten.